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View Full Version : An atmosphere that let in more cosmic rays would it accelerate evolution?



MVAgusta1078RR
2014-May-19, 08:51 AM
We know how cosmic rays affect DNA and mutations and evolution. So on planets where life was exposed to more of cosmic rays does anyone know what the affect might be? Worse? Accelerated? Both?

Strange
2014-May-19, 12:13 PM
The lief forms would probably develop methods to protect themselves from excessively high levels of damage (as organisms on Earth have) so that the level of mutations was enough to produce useful variation but not enough to destroy life. (Unless it was so high that life was impossible.)

Noclevername
2014-May-23, 11:17 AM
Cosmic rays cause mutations by essentially breaking DNA and letting it heal wrong, like a broken bone out of alignment. Of those mutations, nearly all are harmful to the organism, causing cancers. The ones that alter reproductive cells are the only ones that can alter evolution, and those are over 80% lethal. The rest are mostly weaknesses or genetic disorders, or neutral, and only a handful are beneficial or potentially beneficial.

But mutation alone isn't evolution. Evolution is adaptation to species' conditions. So a benign environment will produce less changes than an unstable or reproductively competitive environment. In different conditions a neutral mutation might become a life saver, or vice versa. This, more than rate of mutation, affects the evolution of a gene pool.

cjameshuff
2014-May-24, 01:47 PM
Living things have evolved mechanisms for detecting damage and correcting it or containing the damage by having damaged cells self destruct. The mechanisms aren't perfect, but the resulting mutation rate is likely close to the optimum, since groups with mutation rates further from the optimum wouldn't adapt as fast or as effectively. Drastically increasing the mutation rate would likely lead (eventually) to improved repair mechanisms.

Note that variation of individuals and evolution of groups (in sexually reproducing organisms, anyway) is primarily due to the random mixing of genes from the parents, and a healthy gene pool will support a wide range of variation allowing a great deal of adaptation even without any mutations occurring. In addition, as Noclevername said, the selection forces are what actually drives evolution.